refactor: rename materia → beanflows throughout codebase

- Rename src/materia/ → src/beanflows/ (Python package)
- Rename transform/sqlmesh_materia/ → transform/sqlmesh_beanflows/
- Rename infra/supervisor/materia-supervisor.service → beanflows-supervisor.service
- Rename infra/backup/materia-backup.{service,timer} → beanflows-backup.{service,timer}
- Update all path strings: /opt/materia → /opt/beanflows, /data/materia → /data/beanflows
- Update pyproject.toml: project name, CLI entrypoint, workspace source key
- Update all internal imports from materia.* → beanflows.*
- Update infra scripts: REPO_DIR, service names, systemctl references
- Fix docker-compose.prod.yml: /data/materia → /data/beanflows (bind mount path)

Intentionally left unchanged: Pulumi stack name (materia-infrastructure) and
Hetzner resource names ("materia-key", "managed_by: materia") — these reference
live cloud infrastructure and require separate cloud-side renames.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

transform/sqlmesh_beanflows/models/seeds/weather_locations.sql

@@ -0,0 +1,7 @@
+MODEL (
+  name seeds.weather_locations,
+  kind SEED (
+    path '$root/seeds/weather_locations.csv',
+    csv_settings (delimiter = ';')
+  )
+)